A swirler is used as a flame stabilizer of a pressure atomizing-type oil burner or a high pressure gas current atomizing-type oil burner, and swirls the air introduced into a burner by using swirl vanes. A mixture gas of the air introduced into the burner by the swirler and a fuel generates negative pressure in a center portion, and accordingly, generates a high temperature low-speed circulation region that may be ignited.
Swirlers may be classified as axial flow swirlers and radial flow swirlers.
FIG. 1 is a partially cut perspective view schematically showing an axial flow swirler, as an example of an axial flow swirler. In addition, FIG. 2 is a cross-sectional view of the axial flow swirler of FIG. 1, wherein a side of the axial flow swirler based on a symmetric axis is shown. Referring to FIGS. 1 and 2, an axial flow swirler 10 includes a plurality of vanes 12 that are disposed on an upstream side of a burner 50 on a path of air GA entering a chamber 51 of the burner 50. The plurality of vanes 12 are radially arranged on a boundary of a pilot body 15 to be inclined with respect to an entering path of the air GA so as to change a flow direction of the air entering the chamber 51 of the burner 50. Therefore, the air and the fuel mixed with the air are introduced into the burner while generating a whirlpool.
Such an axial flow swirler has a simple structure and is easy to be manufactured. However, because only a direction of introduction fluid is changed without changing a velocity of the introduction fluid, the performance of mixing the air and the fuel may degrade.
FIG. 3 shows an example of a radial flow swirler and schematically shows a cross-sectional side of the radial flow swirler based on a symmetric axis. A radial flow swirler 20 is disposed at an upstream side of a burner 50 like the axial flow swirler 10, and includes a pilot body 25 and a plurality of vanes 22 coupled to the pilot body 25. Unlike the axial flow swirler 10, in the radial flow swirler 20, the air GA is introduced into the chamber 51 of the burner 50 in a radial direction while a flow direction and velocity of the air are rapidly changed by the vanes 22.
As described above, the radial flow swirler is excellent in view of mixing the air and the fuel due to the rapid change in the velocity of the introduced air, but it is difficult to manufacture the radial flow swirler and to control the flow of fluid, compared to the axial flow swirler.